NOTE: With our Novak style 1911 sights, start with .023" (one pink and one clear) of shim. Amount of needed shim will vary, depending on load and particular barrel. Each increment of .0025” - .0030” of elevation shim will affect bullet impact by approximately 1" at 25 yards. Our Novak style 1911 front sight and rear sight base is a press fit and should be professionally installed. We recommend fitting the rear sight, so that one may easily adjust windage with our rear sight set screw system.